gestion-materiaux-destock/src/app/api/creation/preview/route.ts

import { NextRequest, NextResponse } from 'next/server'
import { getServerSession } from 'next-auth'
import { authOptions } from '@/lib/auth'
import { fetchPendingProducts } from '@/lib/creationSheets'
import { prisma } from '@/lib/prisma'
import type { PendingProduct } from '@/types/creation'

export async function GET(req: NextRequest) {
  const session = await getServerSession(authOptions)
  if (!session) return NextResponse.json({ error: 'Non authentifié' }, { status: 401 })
  const tab = new URL(req.url).searchParams.get('tab') ?? undefined
  try {
    const existing = await prisma.productCreation.findMany({ select: { sheetTab: true, sheetRow: true } })
    const alreadyCreated = new Set(existing.map(e => `${e.sheetTab}:${e.sheetRow}`))
    const pending = await fetchPendingProducts(alreadyCreated, tab)
    const byTab: Record<string, PendingProduct[]> = {}
    const specificColumns = new Set<string>()
    for (const p of pending) {
      if (!byTab[p.tab]) byTab[p.tab] = []
      byTab[p.tab].push(p)
      Object.keys(p.specificFields).forEach(k => specificColumns.add(k))
    }
    return NextResponse.json({ byTab, total: pending.length, specificColumns: Array.from(specificColumns).sort() })
  } catch (err) {
    const message = err instanceof Error ? err.message : 'Erreur inconnue'
    return NextResponse.json({ error: message }, { status: 500 })
  }
}